AUSTIN (KXAN) — The Food and Drug Administration warns antigen tests might not detect the highly-transmissible omicron variant. The agency continues to authorize the use of the tests but said antigen tests are generally less sensitive and less likely to pick up very early infections compared to molecular tests.

Officials said if a person tests negative with an antigen test but is suspected of having COVID-19 — such as experiencing symptoms or having a high likelihood of infection due to exposure — follow-up molecular testing is important for determining a COVID-19 infection.

With Austin-Travis County back under Stage 4 risk-based guidelines, health officials are recommending masks in all situations, even for those who are fully vaccinated and boosted.

Austin Public Health is reporting 70 new hospitalizations in the past 24 hours. That’s why city and county leaders are expanding free COVID-19 testing across Central Texas, including the Long Center.

More lanes were added to reduce wait times after workers did about 1,000 tests Tuesday. Nomi Health said about 26% of those tests came back positive. Health officials continue to encourage PCR tests for those who can get them.

APH said self-administered tests’ reliability can be affected by the person administering the test, because they just don’t want to go deep enough into the nasopharyngeal area to collect an adequate sample.

Ana Lopez told KXAN she tested positive for COVID-19 after getting varying results from at-home tests.

“I’m very paranoid. So I tested again and had a take-home test on the 22nd, and it came back positive, so I have been isolating ever since,” Lopez said.

Jay Kahlon, who was supposed to spend the holidays with family in Austin, said he had a similar result when taking an antigen test and a PCR test.

“I had a rapid test done, which was negative, and then went on to the ER the next day, which was Dec. 18, and at that point, I could barely talk,” he said. “My lips were swollen a little bit, and then I also had a really scratchy throat and an upset stomach.”

He said the doctor did a PCR test and the results were positive.

APH said the gold standard for COVID-19 detection continues to be the PCR test. If a person has COVID-19-like symptoms, they should isolate from others and wear a mask until they are tested.

The Centers for Disease Control and Prevention also recommends if a person tests negative on day five after symptom onset, they should still continue to wear a mask for five days when around other individuals.